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PCI CD and PCI CDa

Document Number: 008-00965-06 EDT Public Revision: I December 2004

Template: edt.dot

Page 29

edt_configure_block_buffers

Description

Similar to edt_configure_ring_buffers, except that it allocates the ring buffers as a single large block,

setting the ring buffer addresses from within that block. This allows reading or writing buffers from/to

a file in single chunks larger than the buffer size, which is sometimes considerable more efficient.

Buffer sizes are rounded up by PAGE_SIZE so that DMA occurs on a page boundary.

Syntax

int edt_configure_block_buffers(EdtDev *edt_p, int bufsize, int

numbufs, int write_flag, int header_size, int header_before)

Arguments

edt_p

device struct returned from edt_open

bufsize

size of the individual buffers

numbufs

number of buffers to create

write_flag

1, if these buffers are set up to go out; 0 otherwise

header_size

if non-zero, additional memory (header_size bytes) will be allocated for each

buffer for Header data. The loocation of this header space is determined by

the argument header_before.

header_before

if non-zero, the header space defined by header_size is placed before the

DMA buffer; otherwise, it comes after the DMA buffer. The value returned by

edt_wait_for_buffers is always the DMA buffer.

Return

0 on success, -1 on failure.

See Also

edt_configure_ring_buffers

edt_startdma_action

Description

Specifies when to perform the action at the start of a dma transfer as specified by edt_startdma_reg(). A

common use of this is to write to a register which signals an external device that dma has started, to

trigger the device to start sending. The default is no dma action. The PDV library uses this function to

send a trigger to a camera a the start of dma. This function allows the register write to occur in a critical

section with the start of dma and at the same time.

Syntax

void edt_startdma_action(EdtDev *edt_p, uint_t val);

Arguments

edt_p

device struct returned from edt_open

val

One of EDT_ACT_NEVER, EDT_ACT_ONCE, or EDT_ACT_ALWAYS

Example

edt_startdma_action(edt_p, EDT_ACT_ALWAYS);

edt_startdma_reg(edt_p, PDV_CMD, PDV_ENABLE_GRAB);

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